Most incandescent bulbs are less energy efficient than LEDs
shutterstock/marina_shikhantsova
Incandescent devices that reuse some of the infrared radiation they emit are as efficient as LED lights, but with lower carbon emissions.
Lighting accounts for about 20% of the world’s electricity use and more than 10% of the carbon footprint. LEDs don’t contribute much to this as they tend to be more energy efficient than incandescent bulbs, but they don’t always reveal the true color of an object. His Kehang Cui and his colleagues at Shanghai Jiao Tong University in China set out to build an incandescent lighting device that does not need to make this trade-off.
Incandescent lamps traditionally work by passing an electric current through a tungsten filament within a glass bulb. In the new device, the researcher used a filament that he had two layers. One is made of atomically thin rolls of carbon called carbon nanotubes, and the other is made of a ceramic material containing boron and nitrogen. I put it in a ceramic box with windows made of a special kind of quartz instead of glass.
The researchers passed an electric current through the two layers of filament, emitting both visible and infrared light. Unlike the glass in the light bulb, the quartz slab didn’t just let all this radiation through, he says. Made of very thin layers of minerals, they are designed to turn back infrared radiation. filament.
Due to this infrared light recycling, the efficiency of the device reached 25.4%. This is on par with common LEDs, but he is more than ten times better than conventional bulbs. Since it was still an incandescent lamp, this device had a higher color rendering index than LEDs. This means that the color of illuminated objects will look nearly identical to how they appear under natural light.
According to Cui, his team’s analysis shows that the lamp is made of relatively simple and readily available materials and can operate for more than 60,000 hours before it fails, meaning that over the lifetime of a single device, The carbon footprint of LED lights is comparable.
“The efficiency of the device is impressive, but it’s a much more complicated device than a traditional incandescent light bulb. It’s probably not cheap to mass-produce,” says Jonathan Wheeler of North Carolina State University. He says it could find some niche uses, but catching up to LEDs without being able to do the functions LEDs could never do would be a big challenge.
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